In the process of making a motherboard, to prevent the motherboard from having problems after being delivered to a customer, a plurality of pretests have to be conducted on the components of the motherboard in advance to check if the components function normally. If the motherboard cannot function normally after being delivered to a customer, the manufacturer of the motherboard may suffer a great financial loss. Therefore, the pretests of the components, such as the pretests of slots (such as a PCI slot), are very important. The slot of the motherboard includes a plurality of power sockets electrically connected in parallel. In a conventional testing technology, due to the parallel connection of the power sockets, it is very hard to determine if one of the power sockets has a defect resulting in a power disconnection between the power socket and an interface card electrically connected thereto, except that all of the power sockets have the defect. When one of the power sockets has the defect, the power socket having the defect does not affect the voltage provided by all of the power sockets. However, shortage of the amount of the power sockets having no defect may decrease the power provided by the power sockets, thereby affecting the function of the interface card.
Therefore, how to design a new test board, which can check if one of the power sockets of the slot has the defect, is a very important problem to be solved.